Migrate from multierr.Combine to errors.Join and update go version

[dashpole]

Fixes #704

This also updates the go version support window from [1.19,1.20] to [1.20,1.21].

From the definition of errors.Join:

Join returns an error that wraps the given errors. Any nil error values are discarded. Join returns nil if every value in errs is nil. The error formats as the concatenation of the strings obtained by calling the Error method of each element of errs, with a newline between each string.

A non-nil error returned by Join implements the Unwrap() []error method.

[codecov]

Codecov Report

Merging #708 (bba89c4) into main (c915721) will increase coverage by 0.20%.
The diff coverage is 59.45%.

@@            Coverage Diff             @@
##             main     #708      +/-   ##
==========================================
+ Coverage   69.39%   69.59%   +0.20%     
==========================================
  Files          36       36              
  Lines        4735     4717      -18     
==========================================
- Hits         3286     3283       -3     
+ Misses       1298     1286      -12     
+ Partials      151      148       -3     

Files Changed	Coverage Δ
exporter/collector/logs.go	45.48% <0.00%> (+0.50%)	⬆️
exporter/collector/metrics.go	73.05% <50.00%> (+0.32%)	⬆️
exporter/metric/metric.go	69.70% <73.07%> (+0.98%)	⬆️
exporter/trace/trace.go	90.16% <100.00%> (-0.75%)	⬇️

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[aabmass]

LGTM if you can get the tests to pass

[dashpole]

I'm going to update the go version (errors.Join was added in 1.20). We support the latest 2 versions, so that should be OK

[anuraaga]

Hi @dashpole - it looks like this was merged and released with go 1.21. Given your last comment, wondering if this was supposed to be go 1.20?

[dashpole]

@anuraaga I went ahead and updated to 1.21, since we support the latest 2 versions of go. Did this cause issues for you?

[anuraaga]

I saw a warning when compiling with 1.20, not sure if there was something special about my build setup. But AFAIK the intent of that flag is for libraries to always set the version in go.mod to the minimum supported so the Go compiler prevents as much as possible incompatibilities when compiling with the older version.